Common-battery rotary-connector system.



Wyn; CAMPBELL. COMMON IBATTERVY'ROTART CONNECTOR SYSTEM.

APPLICATION FILED JUNE 10. I907.

Patentefl Apr. 25,1wm.

STAT T WILSON L. CAMPBELL, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FIRST TRUST AND SAVINGS BANK, TRUSTEE, OF CHICAGO, ILLINOIS.

COMMON-BATTERY ROTARY-CONNECTOR SYSTEM.

Specification of Letters Patent.

Application filed June 10, 1907. Serial No. 378,197.

To all whom it may concern:

Be it known that I, VVILsoN L. CAMPBELL, a citizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Common-Battery Rotary-Connector Systems, of which the fol lowing is a specification.

My invention relates to telephone systems of that character in which so-called rotary connectors are employed for closing the final connection directly with an idle one of a pluralityof lines leading to a called subscribers station. In systems of this kind it is possible to give a subscriber a number of lines, and to automatically select idle lines by means of the rotary connectors. In this way a calling subscriber, in extending connection to the substation of .a subscriber having several lines or trunks, simply causes the rotary connector to pick out the proper group of lines, and the connector then proceeds automatically to pick out an idle one of said lines. In other words, connectors of this character have provisions for automatically selecting idle lines or trunks, somewhat in the manner that idle trunks or trunk lines are selected by the so-called selectors or other automatic trunking switches. Generally stated the object of my invention is the provision of an improved system in which improved and highly eflicient ro tary connectors are employed for automatically picking out or selecting idlelines or trunks leading to the substations of the called subscribers. It will thus be seen that my invention is in the nature of an improvement on the application of T. G. Martin Serial No. 364,699, filed March 26, 1907, in which application the broad features of a rotary connector are being claimed.

A special object is to provide a common battery rotary connector system in which the said rotary connectors are equipped with means for controlling the supply of talking current to the line circuits, and in which the supply of talking current to the called subscribers substations is controlled by the called subscribers, the calling substations being without talking current until the called subscribers answer.

It is also an. object, of course, to provide certain details and features of improvement and combinations tending to increase the general eliieiency and serviceability of a common battery rotary connector svstem of this particular character. i

To the foregoing and other useful ends, my invention consists in matters hereinafter set forth and claimed.

The accompanying drawing shows diagrammatically a calling substation A and a called substation A connected through the meduunof a common battery central station equipment comprising rotary connector switches. In the said central station the calllng substation #500 has allotted to its line the first-selector C, which is of the type disclosed in United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson. It will be seen that the central battery B has its'positive terminal preferably grounded at G. The operating relays of the central switches are normally connected to the nongrounded terminal of said battery, so that the subscrlber may operate the said switches by grounding his line conductor, as is usually the custom in systems of this type. In ad dition to the first-selector C there isshown at I) a common battery rotary connector switch embodying the principles of my invention, and at F. is shown another firstselector similar to the selector C allotted to the called line. In this system both the calling and called substations are provided with battery current for talking purposes only when the called subscriber answers.

In this system each subscribers line is, of course, provided with a first-selector switch C. These selectors, as is well known, are used for obtaining connection with some connector, through the medium of which connector any one of a hundred subscribers will be reached. The subscribers first-selectors are, as is ordinarily the case, ar ranged in groups of one hundred. The connector switches are also arranged in groups, each group being provided for taking care of one hundred subscribers-.-that is, if any subscriber in the system wants to call auother" subscriber in the system. he must, through the medium of his selector, pick out a certain group of connectors, any one of the connectors of which group is capable of establishing the final connection with the de sired subscriber in a particular hundred. In a system where rotary connectors are used, as. for example, the system herein illu trated and described, it is not necessary that Patented Ap1a25, rare. i

. when the receiver is removed.

all of the connector switches be of the-rotary type.

In practice, the ordinary arrange ment is'to allot the rotar connectors to one bank level ofsthe first-se ector switches. It

isunderstood, of course, that the selectors of the type in connection with which I have described my invention are equipped with banks of-contacts, and that these contacts are arranged in levels, each level containing ten sets of bank contacts toeach of which sets one connector switch is allotted. The

remaining nine levels of the first-selector banks are provided with trunks toother connector switches of any known or approved *type, for example, connector switches of the general type described in United States Let-' ters Patent No."815,1' 76, granted Marcli 13, 1906, to Keith, Erickson and Erickson. With this arrangement each group of connectors. thatis accessible from the bank levels of the first selectors, as previously stated, takes care-0t one hundred subscribers, so that in.

the system so far describedthat is, where only first-selectors and connectors are usedthe maximu'm number of subscribers that would ordinarily be accommodated is one thousand.

The substations may be of any suitable 01-.

approved type. The substation A, for example, comprises a receiver 2, a-switch-hook 3,-

inductioncoil 4 which consists of the primary wind ng and secondary winding 6, transmitter 7,- condenser 8, ringer 9, impulse wheel 10 which has the usual vertical im,-' pulse teeth 11 that are adapted to operate the vertical impulse spring 12. The impulse wheel carries the rotary impulse tooth 13 which operates the rotary impulse spring 14.

The switch-hook has-radiating 'from its body a number of cam-arms 15, 16 and 17, and is pivotally secured to. the keyboard -(not shown) at the point 1S about which it moves The move ment is'produced by a spring (not shown),

and the switch-hook is pushed up for the purpose of changing certain circuit connections to be disclosed. The canrarm 15 controls the SQ-callGcldockiIlg cam 19. Before the dial is rotated the locking cam- 19 occu- 0 pies the position shown at substation A, but

after the dial is turned the cam 19 rests in the position shown at substation A, permitting the ground springs 20 and 21 to engage, and thus placing the ground post 22 5 in connection with the substation ground G,

whereby when the subscriber releases the dial after rotating it thevertical impulse teeth 11 will cause the verticallim'pulse spring 12 to come in contact with the ground to post 22; and immediately thereafter the'rotary impulse tooth 13 causes the rotary impulse spring 14 to come in contactwith the same ground post 22, thus sending ground impulses to the central station for operating I at the switches thereof. But while the switchhook is downthe cam-arm 17 maintains a contact betweenthe springs 23 and 24, there by bridging the condenser 8 in series with the ringer 9 across the line, and keeping the springs25:and 26 disengaged, whereby the primarycircuit including the winding 5 in series with the transmitter 7, is interrupted. The signaling device, whereby a subscriber may-signal another after a connection has been established, comprises a. push-button 28 and a spring 29, which latter normally engages the contact point 30; but ;when the push-button 28 is pressed the spring 29 leaves the contact point 39 and engages the contact point 31 which is connected with the 8C substation ground'G. Means whereby the subscriber may release the central station apparatus brought into service comprises three springs 32,33 and 34,'known as'the release springs, which are socontrolled by the C LlIt-ZLIID 16 that when the switch-hook descends the three release springs are brought into contact for a moment, 'tliereby grounding both the subscribers lineconductors 36 and '37 simultaneously. 4

The first-selector switch shown at C, being of the type described in said selector patent, is well known and needs only general description. The switch-shaft (not shown) carries the vertical and rotary wipers 39 and 40, respectively, and the private wiper 41. The side switch is well known and comprises the side switch wipers 42, 43, 44 and 45 which may be designated as vertical, rotary and private side switch 1 wipers andthe rotary magnet side switch wiper, respectively. The side switch isun- 'der the control of the private magnet 46,

and through the medium of the vertical line relay -47 the subscriber controls the vertical magnet 48, while the side switch is in first position, which latter magnet operates to raise the shaft and shaft wipers 39, 40 and 41 vertically. The private magnet is, however, controlled through the niedium ofthe rotary line relay 49. While the side switch is in second position the rotary magnet 50, which carries the shaft and shaft wipers in a rotary or circular direction, is energized in a localcircuit, and the vertical and rotary line relays- 47 and 49 acting conjoint-1y provide means whereby the subscriber controls the release magnet 51 while the said side switch is in first or second position.

However, after the sideswit-ch passes to 130 third-position, then, since the first-selector is of the trunk-release type, the said switch is controlled through the medium of the nextswitch D, with. which a connection is established, over a circuit comprising the private wiper 41 and the back-release relay 52. The bridgc-cut-ofi relay 53 is provided to open-the connection between the line relays 47 and 49, and between said relays and battery B. This is desirable, because if the relays are not disconnected from each other and battery, the ringing current for signaling the subscriber may throw the selector switch C off normal. It is also desirable to remove the bridge formed through the said relays from across the line to give the voice-currents as clear a path as possible. The first-selector switch shaft is also provided with a normal post arm 54 which, when the shaft is in normal position, closes the spring 55 in contact with the contact point 56; but when the shaft is raised one or more steps the spring 55 closes in contact with the contact point 57, by which switching means the switch is made busy while off normal, and the energizing circuit for the bridge cut-off relay 53 is controlled.

The connector svitch D is an improvement upon the connector switch disclosed in said connector patent, since in the connector D I provide means whereby the connector shaft may be automatically rotated, like the shaft of the first-selector, when the private wiper engages grounded contact points.

My improved connector combines in a common battery switch the general features of the connector disclosed in said last-mentioned patent with the selector features of the first-selector disclosed in said other patent. The mechanical details of the selector and connector, as is well known, are very similar. The connector switch shaft (not shown), like the selector, carries the line wipers c9 and and theprivate wiper 71. The connector switch is also controlled by the calling subscriber through the medium of the vertical and rotary line relays 72 and 73. The vertical line relay 72 directly controls the vertical magnet 74 and also the rotary magnet 75. The purpose of the vertical magnet 74L is to give the shaft and shaft wipers a vertical motion, and the rotary magnet 75 imparts to the shaft and shaft wipers a rotary or circular motion. The rotary line relay 73 controls the private magnet 76, which latter, under certain conditions, controls in turn the vertical and rotary magnets 7-? and 75 and also the side switch wipers 77, 78, 7t), and 81. The private magnet 76, as I have arranged it to operate in the connector switch 1), plays a very im 'iortant part, and controls the rotary action to a great extent. The object in providing the connector with this auto matic selective feature is as follows: A business house or private branch exchange, for example, may be provided with three lines, all of which are given the same number, and it may become desirable to so arrange the system that if one line is in use the calling switch will automatically carry the calling subscriber into connection with the second line; if the second line is also busy; the connection may be carried to a third line, and so on. The calling subscriber would, of course, have no control over the apparatus as to which. one of the lines he makes connection with. This, however, does not concern him, since any trunk line to the said office or private branch exchange will serve his purpose.

The arrangement of the connector banks themselves will'be as follows: If the ofiice to which the number 121 is allotted (see Fig. 1) wishes two telephones, it will be given two lines, one terminating in the first con tact of the second level of the connector banks, and the other in the second contact of the second level. Now, if-the number 121 is called, the connector is raised to the second level and then rotated into engagement with the first contact of the second level; but if the said contact is busy the connector is automatically-rotated onto the second set of contacts. It becomes desirable, of course, to provide means for notifying the subscriber in the event that all the lines are busy. For this purpose the third set of bank contacts of the second level are connected with a busysignaling circuit, at which contacts the connector must stop in the event that all lines are busy. A busysignaling current is then sent to the calling subscribers line over a circuit including the third set of contacts of this level. This arangement is not confined to any level, as any level may be divided in the same way, and any subscriber may thus be given any number of lines, depending on the number of contacts in each level. The side switch of the connector, like the side switch of'the selector, has a normal or first position, a second position and a third position, and also has a release magnet 35 controlled by the vertical and rotary line relays 72 and 73 conjointly. The condensers 82 and 83 of the connector divide the circuit through it into two sections to separate the calling and called'subscribers talking current feeding circuits, for well known reasons. The connector is provided with a differentially wound relay 84 which comprises the win(l-' ings 85 and 86. The function of this relay is to enable the calling subscriber to rele: se, and to enable him to energize the ringer relay 88 for signaling. Said relay is the means by which the ringer generator F is bridged across the terminals of the called line to signal the -alled subscriber. The back-bridge relay 87, comprising the windings 89 and 90, controls the supply of talking battery current to the calling subscribefs line when the primary circuit of the called substation is bridged across the line. The central station is equipped with the busy-signaling apparatus H. of any suitable design. as. for example, the one comprising an interriu'iter 9] in series with the primary winding 92 of the induction-coil 93, whereby a busysignaling' current is induced in the secondary winding 94 of the said induction-coil.

The operation of the system may be more clearly disclosed if each step during the process of a call is followed in detail, as in the following: itwill be assumed. that the subscriber at substation A wishes to call the office which is registered as #121, and

i which is provided with substations A, A

and A of which only substation A is shown, When the receiver 2 is removed from the switch-hook 3 the cam-arm 17 permits the springs 23 and 24 to disengage, and

' the springs 25 and 26 to engage, thereby re-. moving the ringer 9 from across the line and bridging instead the primary circult.

v r The first digit being 1 the subscriber operates his dial accordingly, and as soon as the dial is drawn down e ground'springs 20 and 21 come into contact, establishing a ground connection from the substatlon ground G to the ground post 22. As thedial returns the impulse wheel 10, by means of the first of the vertical impulse teeth 11, thrusts the vertical impulse spring 12 against the ground. post 22 once, and then by means of the rotary impulse tooth 13, in a similar manner, presses-the rotary impulse spring 14 onto the ground post once. The line conductors 36 and C is first energized by a flow of current from the substation 'round G throu h the round springs 20 and 21 to the vertical impulse spring 12, thence to the vertical .line conductor 36, side switch wiper 42, contact point 94, vertical line relay 47, bridge-'cutoil-relay springs '95 and 96 to the'battery lead 97, and through battery B to ground G. The vertical line relay 47 then, upon operating once, presses the line' relay springs- 08 and 99 in contact, thus energizing the vertical magnet 48 once by a flow of current from ground G through the springs 98 and 90, private springs 100 and 101 to the vertical magnet 48, thence to the battery lead 97, and through battery B to ground G. The vertical. magnet 48, therefore, operates to raise the shaft wipers 39, 40 and 41 to thefirst level,-in the well-known manner.

when the This operation having been accomplished, rotary line conductor 37 is grounded the rotary line relay 49 is energized and this in turn operates the private magnet 46, which latter then trips the side switch to second position, establishing an energizing circuit through the rotary magnet 50 for rotatingthe wipers onto" some trunk line.

The energizing circuit through the said I rotary line relay49 extends from the suba station ground G to the ground post 22,

thence to the rotary impulse spring 14, rotary line-conductor 37, side switch wlper 0a are, therefore, -each grounded once, and as re-- ,sult the vertical line relay 47 of the selector 43, contact point 102, rotary line relay 49, bridge-cut-ofi' relay springs 103, 95 and 9G to the battery lead 97, thence through battery B to ground G. The said rotary line relay, upon pressing the spring 104 onto the spring 98, closes an energizing circuit through the private magnet 40, as already stated, from ground G through the springs 98 and 104, private magnet 46 to the batwiper 45, interrupter springs 106, rotary magnet 50 to the battery lead 97,. thence through battery B to ground G1 The rotary magnet is then energized and the wipers 39, 40 and 41 are carried into engagement with the first trunk. If the said trunk isnot busy the armature of the rotary magnet 50, by mechanically operating the armature of the private magnet 46, releases the side switch to third position; but if the said trunk is busy :1. private contact thereof is grounded and the private magnet energizes at the same time that the private armature is depressed, so that the side switch is held in second position, and an energizing circuit through the rotary magnet 50 is maintained until the private wiper.

41 is carried onto the idle trunk and the energizing circuit for the private magnet destroyed. At the same. instant, of course, the side switch passes to third position, and the wiper 45 leaves the contact point 105, thus breaking the energizing circuit for the rotary magnet 50 and bringing the selector to a standstill. The passage of the side switch to third position carries the side switch wipers 42 and 43 onto the contact points 107 and 10S, and the line conductors 36 and 3'? are placed in. connection with the line wipers 39 and 40 which, having already entered into connection with the trunk cou ductors 109 and 110 that lead to the connector D, place the said conductors 3,0 and 37 also in connection with the said connector D. The passage'of the side switch to third position, furthermore, establishes a guarding potential at the private wiper 41,whe1r the side switch wiper 44 engages the grounded contact point 111, to protect the seized line.

This potential arrives at the said private wiper 41 from ground G to the contact point 111, through the back-release relay 52 to the private wiper 41. The line conductors 36 and 37 having thus been extended to the connector D, the succeeding impulses from the substation A are directed to said connector I). The second digit being 2 the subscriber operates his dial accordingly, grounding the vertical line conductor 3o twice and the rotary line conductor 37 once. Each time that the vertical line conductor 36 is grounded the vertical line relay 72 of the connector D is energized by a flow of current from the substation ground G to the vertical line conductor 36, thence through the selector side switch 42, contact point 107, vertical line wiper 39, vertical trunk conductor 109, vertical line relay 72, side switch. wiper 77, and contact 156, to the battery lead 97, and through battery B to ground G. Each time that the vertical line relay 72 attracts its armature it forces the'line relay springs 112 and 113 into contact, each time sending an impulse through the vertical magnet 74 from ground G thrc ugh the said springs 112 and 113, side switch wiper 80, contact point 118*, through the vertical magnet 74, differential relay springs 11 1 and 115, thence to battery lead 97 and through battery B to ground G. As disclosed in the aforesaid connector patent, the vertical magnet when energized operates to raise the switch shaft and wipers. The vertical magnet 74 being energized twice, the wipers 69, 70 and 71 are raised to the second level. The ground impulse to the rotary line conductor 37, after the switch shaft has been raised, energizes the rotary line relay 73 of the connector,

, which in turn operates to energize the private magnet 76. The circuit over which the said rotary line relay 73 is energized extends from the substation ground (-lto the rotary line conductor 37, thence to the side switch wiper 43 of the selector C, contact point 108, rotary line wiper 40, rotary trunk conductor 110 to the said rotary line relay 73, thence through the winding 86 of the dilferential relay 84, relay springs 117 and 118, to battery lead 97 and through battery B to ground G.

The rotary line relay 73, upon attracting its armature for a moment, forces the spring 119 onto the spring 112 for a moment,

whereby a flow of current is sent through the private magnet 76 from ground G through the springs 112 and 119 to the private magnet 76, differential relay springs 117 and 118 to the battery lead 97, thence through battery B to ground G. The pri vate magnet 76, upon attracting its armature and then deenergizing, operates to release the side switch from first to second position, as disclosed in said patent. The effect of the shifting of the side switch is to substitute the rotary magnet 75 for the vertical magnet 74, and bring it under the control of the vertical line relay 72, when the side switch wiper 80 leave the contact point point 120, through the rotary magnet 75,

differential relay springs 114 and 115,- thence to the battery lead 97 and through battery B to ground G. The rotary magnet 75 be ing energized once, the shaft is rotated one step in the manner disclosed in said patent, whereby the wipers 69, 7 O and 71 are carried into engagement with the first terminal of the second level, from. which terminal lead the normal conductors 129, 130 and 131 that extend to the selector E of the called line, the former two, of which conductors continue through to the called substation #121. After the connector has thus been operated, the ground impulse to the rotary line conductor 37 energizes the rotary line relay 73 of the connector over circuits that are a! ready well known, which relay in turn operates the private magnet 7 6 as before. Now when the last rotary impulse operates the rotary line relay 7 3 one of two results occursthe release of the side switch from second to third position, or the connector shaft is automatically rotated onto the next set of contacts, providing the first set of contacts is busy, and into connection with asecond trunk line. Furthermore, if all of the trunk lines to which the number 121 is allotted are engaged, the shaft wipers are rotated onto a set of contacts to which the busy-signaling machine H is connected, and

the calling subscriber receives the busy signal.- This automatic rotation is brought about as follows: When the private magnet 76 energizes, as previously explained, it is maintained energized if the first private con tact is grounded-that is, if the first trunk line is in use. The locking or holding circuit for the private magnet extends from the grounded contact to the private wiper 71, side switch wiper 81, contact point 132, conductor 133, private magnet springs 184 and 135, private magnet 76, through the differential relay springs 117 and 118 to the battery lead 97, thence through battery B to ground'G. The private magnet 76 is thus energized by a locking circuit, and retains the side switch wipers in second position as long as the wiper 71 engages a busy or grounded contact. Furthermore, when the private magnet is energized the spring 136 is shifted into contact with the spring 137, whereby a new energizing circuit is broken, whereby the said magnet deenergizes' and the side switch passes to third position.

If the first set of contacts is not in use there is no ground potential at the private wiper 71 to lock and hold the private magnet when the last rotary impulse comes, and, there fore, the side switch passesto third position. passes to third position, whether on the-first line or after having rotated, and when the side switch wiper 81 engages the contact point 139, a guarding potential is estab' lished at the connector private bank, for

protecting the seized line. Also, when the side switch wiper ,81 passes to'third position an energizing circuit is closed through the bridge-cutoff relay 140 of the' selector E, whereby the vertical and rotary line relays 141 and 142 are disconnected from each other and from the battery lead. This circut extends from ground G through the side switch wiper 81, shaft private wiper 71, conductor 143, normal springs 144 and 145,

through the bridge-cut-off relay 140 to the battery lead 97, thence through battery 13 to ground G.

Assuming that all of the lines allotted to making connection witli' one of the lines, as explained, the shaft w1pers 69, 70 and 71 are automatically rotated to the .contact points 146, 147 and 148, respectively. The connector stops here, because, as willbe seen, the private-contact 148 is insulated and the energizing circuit for the private magnet is broken. When this occurs an energizing circuit is established including the relay 149 and the"winding 90 of the differential relay This circuit extends from ground Gr through the side switch wiper 81, winding 90 of the relay 87, ringer relay springs 151 and 152, side switch wiper 7 9, contact point 153, shaft wiper 70, contact point 147, relay 149 to the battery lead 97, thence through battery. B to ground G. The winding 90,

upon carrying current, energizes the relay 87 which operates, but at this particular time without effect. The relay 149 operates to place the springs 154 and 155 in contact,

and thus the busy-signaling machine H is connected to the. vertical bank contact 146, whereby the busy-s1gnaling current is sent to the calling subscriber, It will be seen In any event, when the side switch' switch wiper 81 will not-establish a 'guarding potential, calhngthe same number and findin all the Therefore, other-connectors trunk lines occupiedmay alsosto on the bank contacts 146, 147 and 148 an receive .the busy-signal. .Furthermore, whenthe connector side switch passes fromsecond to third position, the side switch wiper 77 passes from the contact point 156 to the'con tact point 157, whereby the vertical line -re-" lay 72 becomes disconnected from the battery lead 97 and connected with the winding 85 of the differential relay 84, whichla'tter is connected with the battery lead 97; and.

then when the vertical line relay 7 2 is energized the winding also carries current.

The two substations Aland A having been connected, as explained, the subscriber at substation A then signals the called subscriber. To signal the called subscriber the.

subscriber at substation A presses thesignalingbutton 28, wherebythe vertical line cons ductor '36 is grounded and the connector.

vertical line relay 72 and the differential re lay 84 become energized. It will be rememthat the side'switch wiper 80 is in engagement with the contact point 158, thereby placing the vertical line relay 72 in control of the ringer relay 88 in .the same manner 1n which the rotary magnet 75 came under .the control of the vertical line relay when contact', the ringer relay 88 is then ener-' the number 121 are busy, then instead of gized by a flow of current from ground Gr through the springs 112 and 113, side switch wiper 80, contact point 158, ringer relay 88, springs 116 and 115 (bearing in mind that the differential relay 84 is energized), to

the battery lead 97, thence. through batteryv .bered that the connector side switch has passed from second to third" position, and" is, therefore, sentfr'om the generator F. to

the ringer relay springs 161 and 160, side switch wiper 78, contact point 162, shaft wiper 69, normal conductor 129, vertical line conductor 163, condenser 164, ringer 165, springs 166 and 167, to the rotary line conductor 168, rotary normal conductor 130, shaft wiper 70, contact point 153, side switch wiper 79, ringer relay springs 152 and 159 back to the ,generator F. As soon as the calling subscriber ceases to press the signaling button 28 the ringer relay 88 becomes deenergized and the springs 152 and resume their normal positions. The sub scriber at substation A, in response to the signal, removes the receiver 169 from the switch-hook 170, which allows the springs 171 and 172 to engage, and the springs 166 and 167 to dis-*tzguge, thereby removing the ringer 165 from across his line. The engagement of the springs 171 and 172 closes a a series energizing circuit through both windings of the relay 87 at the connector D, said circuit extending from ground G to the contact point 139, side switch wiper 81, winding 90 of the relay 87, through the ringer springs 151 and 152, side switch wiper 79, contact point 153, shaft wiper 70, rotary normal conductor 130, rotary line conductor 168, primary winding 173, transmitter 174, through the signaling device of the called substation, through the springs 171 and 172,

vertical line conductor 163, conductor 129, shaft wiper 69, contact point 162, wiper 78, through the winding 89 of the relay 87, springs 114 and 115 to the battery lead 97, thence through battery B to ground G.

The relay 87 upon energizing operates to shift the spring 117 from the spring 118 (which is connected to the battery lead 97) to the spring 17 5, which is in turn connected with ground. This reversal of the polarity of the spring 117 sets up a circuit which provides the calling substation with battery current for talking purposes. This circuit may be traced from ground G to the contact point 139, side switch wiper 81, through ,the springs 175 and 117, winding 86 of the differential relay 84, rotary line relay 73, conductor 110, shaft wiper 40, rotary line conductor 37, primary winding 5, transmitter 7 springs 25 and 26. vertical line conductor 36, shaft wiper 39, conductor 109, vertical line relay 72, side switch wiper 77, contact point 157, winding 85 of the differential relay 84 to the battery lead 97, thence through battery B to ground G. Both windings of the differential relay 84 being thus supplied with current, the said relay does not operatively energize. The two substations being thus supplied with battery current, the subscribers may carry on conversation over the conductors shown by heavy lines. v

The release of the switching apparatus is brought about when the calling subscriber restores the receiver 2 to the switch-hook 3,

relay 84, extending from ground G at the connector to the contact point 139, side switch wiper 81, springs 175 and 117, winding 86 ot' the diii'erential relay 84, rotary spring 175 and into engagement with thespring 118, which removes the said shortcircuit of the rotary line relay 73 and wind ing 86 and establishes an energizing circuit instead which extends from the substation ground G through the release springs 32 and 33 to the rotary line conductor 37, thence to the rotary line relay 7 3, as previously traced, winding 86 of the differential relay 84, through the springs 117 and 118 to the battery lead 97, thence through bat-- tery B to ground G. The rotary line relay 73 now operates and the springs 176 and 177 come into contact, whereby an energizing circuit is established through the release magnet 35 of the connecto. l), in series with the release relay 52 of the selector C. It will be seen that the current now in passing, as above stated, through the winding 86, aids the winding 85 in maintaining the springs 115 and 116 in contact. The energizing circuit through the release relay 52 and release magnet 35 extends from ground G at the selector C, private side switch wi er 44 release relay 52 shaft wi J61 41, 7 1 l magnet 35 is thus supplied with current it energizes, and as a result the switch shaft and side switch are restored to normal position, thus breaking the connection between the connector switch shaft wipers 69, and 71 and the normal conductors 129, 130 and 131. The back-release relay 52, being in the same circuit with the release magnet, energizes simultaneously with the .latter and operates to close a circuit through the selector release magnet 51 by pressing the back-release springs 178 and 179 together. The circuit through the said release magnet 51 extends from ground through the springs 178 and 179 to the release magnet 51, thence to the battery lead 97 and through battery B to'ground G. When the ground to the line conductors 36 and37 is interrupted all the magnets involved in the release are deenergized and all the switches v are fully restored.

. The calling subscriber may, of course, re-

lease the switches if the called subscriber does not answer, but in that case the apparatus works a little differently, the difference being that if the calledsubscriber does not answer, the back-bridge'relay 87 is not energized, and the'line relays 72 and 73 in series with the respective differential relay windings 85 and 86 are connected to the non-grounded terminal of battery B. It.

will be evident, of course, that these condifor other cases that is, when the subscriber tions also exist in like manner when all the lines to the desired oiiice are busy; In this case that is, when allvthe lines are busy of course, the called subscriber does not answer and the same description willapply does not answer for any reason. Therefore,

when the calling subscriber hangs up his receiver 2 and grounds the vertical and rotary line conductors 36 and 37 simultaneously, the line relays 72 and 7 3 and the differential relay .84 (which have up to this time been denergized, the called subscriber not having answered) become energized simultaneously. As already described, when the line relays 72 and 73 and the differential relay 84 energize, a release circuit is estab' switch of the connector is in first or second position; for in ti -at casethe line relays 72 and 73' and the differential relay 84 will energize simultaneously, causing the release of the switches as above. It will be seen, however, that when the side switch is in first or second position the vertical line relay 7 2 gets potential from the non-grounded pole of the batterythat is, directly and not through the winding 85 of the differential relay 84, as is the case when the side switch is in third position. This makes no difference, however, since the current that'passes through the winding 86 is sufiicient to energize the differential relay 84, whereby the release magnet35 is connected tothe nongrounded pole of the battery through the differential relay springs 116 and 115, as in the previous cases. The subscriber may also attempt to releasebefore the selector switch C has passed into connection with' the connector switch D, in which'case the line relays 47 and 49 will become energized simulta neously, as well as the private magnet 46.

In that case the release magnet 51 of. the

selector C is energized by a circuit extending from ground Gr through the springs 98 and 99 to the private spring 100, thence to the upper spring (the priyate magnet 45 being C and the connectors.

energized,) and through the release magnet 51 to battery 13.

It will be apparent that the telephone sysswitch C or, if desired, the connection may I not be made directly to said connectors, but second-selectors, similar to the first-selectors C, may be interposed between the first-selector These second-selectors will, of course, have to be modified to the extent that the line relays will, in addition, have to be provided with trunlerelease springs, suchcas the springs 176 and 177 of thev connector swji'tch D, the release magnet being connected directly to one of these springs, and the other spring being connected directly to the third or trunk-release conductor, as is ordinarily done.

The windings of the vertical and rotary line relays 72 and 73 and of the dilierential relay S4 and the back-bridge relay 87 may be varied in any suitable manner. Good results may, however,be obtained if the line relays 72 and 73 are wound to a resistance of one hundred ohms, and the windings of the 'diflerential relay 84- to about two hundred and fifty ohms each. The windings 89 and 90 of the back-bridge relay 87 may be given a resistance of three hundred and fifty ohms each.

. From the foregoing it will be seen that I provide common battery rotary connectors for controlling the flow of talking current to the line circuits, and that the supply of talking current to the calling subscribers talking current to the lines of the calling subscribers, and, as retardation for preventing passage of'the voice-currents through the battery. This is also true of the line relays of the said rotary connectors, and the windings of the back-bridge relays serve in a similar capacity with respect to the lines of the called subscribers. I When a subscriber calls another subscriber having several lines or trunks, a rotary connector is first employed for picking'out (r selecting the group of lines or trunks leaning to the called substation, and as soon as this is done the rotary connector then practically escapes fromthe control of the calling subscriber and proceeds automatically to pick out or select an idle one .of said lines or trunks, providingthe same are not all busy. Thus, in 'addition to its functions of regulating or manners controlling the supply of talking current to the line circuits, the said connectors have the further and valuable function of auto matically selecting idle lines or trunks, whenever they are used for calling substations having a plurality of lines or trunks leading thereto.

l/Vhat I claim as my invention is 1. A telephone system comprising a subscribers station, a plurality of lines leading thereto, a rotary connector provided with means for automatically selecting an idle line leading to the called substation, means for supplying talking current through the said connector to the line of the called subscriber, a ringer relay normally closing the talking circuit at the connector, and means by which the called subscriber controls the supply of talking current to the substation of the calling subscriber. 4

2. A telephone system comprising a called subscribers station, a plurality of lines leading to said substation, a rotary connector provided with means for automatically selecting an idle line leading to the called subscribers substation, a dilierential relay for said connector, means for supplying talking current through the windings of said differential relay to the substation of the calling subscriber, a ringer relay which opens the line circuit when energized, and means by which the called subscriber controls the supply of talking current to the substation of the calling subscriber.

3. A telephone system comprising a plurality of lines, an automatic switch provided with means for automatically selecting an idle one of said lines, a calling subscribers line, a called'subscribers substation, a ringer relay which opens the line circuit when energized, and means in and a part of said switch responsive to the called sub scribe'r for controlling the supply of talking current to the calling subscribers line.

4. A telephone system comprising a call ing substation, a called substation, a plurality of trunks, an automatic switch provided with means for automatically selecting an idle one of said trunks, relays in said switch, means for supplying talking currentthrough the windings of said relays to the calling substation, a ringer relay which opens the line circuit when energized, and another relay in and a part of said switch and responsive to the called subscriber for controlling the supply of talking current to the substation of the calling subscriber.

5. The combination of trunks, a switch having provisions for automatic rotation to automatically select idle trunks, a calling subscribers substation, a called subscribers substation, a ringer relay which opens the line circuit when energized, and means in and a part of said switch: and responsive to the called subscriber for controlling the sir ply of talking current to thel substation o the calling subscriber.

6. In a telephone system, a connector re lease magnet, an energizing circuit. for said release magnet, a" vertical magnet, an'energizing circuit for said vertical magnet, a rotary magnet, an energizing circuit tor said rotary magnet, a difi'erential relay, provided with means for breaking the energizing circuit of the said vertical androtary magnets 7 and then closing the energizing circuit of the release magnet, an energizing circuit for said difl erential relay, a subscribers tele phone, and means at said telephone for 330mm trolling the energizing circuit oi. said elifi'er ential relay. l

7. In a telephone system, an automatic switch including a release magnet, an ener gizing circuit for said release 'magnet', vertical magnet, an energizing circuitifor said vertical magnet, a rotary magnet, an energizing circuit for said rotary magnet, a diflerential relay for controlling the circuits of said magnets, an energizing circuit for said differential relay, a subscribers station, and means at said substation for con-- trolling the energizing circuit of said differential relay. I p

8. In a telephone system, a connector re lease magnet, an energizing circuit for said release magnet, a vertical magnet, an ener gizing circuit for said vertical magnet, a rotary magnet, an energizing circuit for said rotary m'agnetyand a differential re-- lay provided with means for breaking the energizing circuits ofthe said vertical and rotary magnets and then closing the energizing circuit of the release magnet, as set forth.

9. In a telephone system, an automatic switch including a release magnet, in energizing circuit for said release magnet, a verti wal magnet, an energizing circuit for said vertical magnet, a rotary magnet, an energizing circuit for said rotary magnet, and a differential relay for controlling the circuits of said magnets.

10. In a telephone system, a connector release magnet, an energizing circuit for said release magnet, a vertical-magnet, an energizing circuit for said vertical magnet, a rotary magnet, an energizing circuit for said rotary magnet, a differential relay provided with means for breaking the energizing circuits of the said vertical and rotary 12 magnets and then closing the energizing circuit of the release magnet, an energizing circuit for said differential relay, and a sub-- scribers station equipped with means for controlling the energizing circuit of said diii'erential relay.

11. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, a rotary magnet, an energizing circuit for said rotary magnet, a differential relay for controlling the circuits of said magnets, an energizing circuit for said differential relay, and a subscribers station equipped with means for coning circuit of the release magnet, an energizing circuit for said differential relay, and substation means for controlling the energizing circuit of said differential relay.

13. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, a differential relay for controlling the circuits of said magnets, an energizing circuit for said relay, a subscribers substation, and means at said sub station for controlling the energizing circuit ofsaid differential relay.

1 1. In a telephone system, a connector release magnet, an energizing circuit for said release'magnet, a vertical magnet, an energizing circuit for said vertical magnet, and a di fierentialrelay provided with means for breaking the energizing circuit of the said vertical magnet andthen closing the energizing circuit, of the release magnet, as set forth. 1

15. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, and a differential relay for controlling? the circuits of said magnets.

16. In a telephone system, a connector re-' lease magnet, an energizing circuit for said releasemagnet, a vertical magnet, an energizing circuit for said vertical magnet, a differential relay provided with means for breaking the energizing circuit of the said vertical magnet and closing the energizing circuit of the release magnet, an energizing circuit for said differential relay, and a subscribers station equipped with means for controlling the energizing circuit of said differential relay.

17. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a vertical magnet, anenergizing circuit for said vertical magnet, a differential relay for controlling the circuits of said magnets, and an energizing circuit for said differential .said release magnet, a rotary magnet, an

energizing circuit for said rotary magnet, a differential relay provided w th means for breaking the energizing circuit of the rotary magnet and then closing the energizing circuit of the release magnet, an energizing circuit for said differential relay, a sub scribers telephone, and means at said telephone for controlling the energizing circuit of said differential relay.

19. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a rotary magnet, an energizing circuit for said rotary magnet, a differential relay for controlling the circuits of said magnets, an energizing circuit for said differential relay, a subscribers station, and means at said station for controlling the energizing circuit of said differential relay.

20. In a telephone system, a connector release magnet, an energizing circuit for said release magnet, a rotary magnet, an energizing circuit for said rotary magnet, and a differential relay provided with means for breaking the energizing circuit of the rotary magnet and then closing the energizing circuit of the release magnet, as set forth.

21. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a rotary-magnet, an energizing circuit for said rotary magnet, and a differential relay for controlling the circuits of said magnets.

22. In a telephone system, a connector release magnet, an energizing circuit for said release magnet, a rotary magnet, an energizing circuit for said rotary magnet, a differential relay provided with means for 'breaking the energizing circuit of the said rotary magnet and then closing the energizing circuit of the release magnet, an energizing circuit for said differential relay, and a subscribers station equipped with means for controlling the energizing circuit of said differential relay.

23. In a telephone system, an automatic switch including a release magnet, an energizing circuit for said release magnet, a rotary magnet, an energizing circuit for said rotary magnet, a differential relay for controlling the circuits of said magnets, an energizing circuit for said differential relay, and a subscribers station equipped with means for controlling the energizing circuit of said differential relay.

24. In a telephone system, aswitching apparatus, operating magnets for said switching apparatuavnormal connections to battery for said operating magnets, electromagnetic releasing means for the switching apparatus, a subscribers station, means at' the subscribers station for operating said electromagnetic releasing means, and means whereby when the subscriber initiates the release the said connections to battery are opened.

25. In a telephone system, a switching apparatus, a rotary operating magnet, a normal connection to battery for said operating magnet, electromagnetic releasing means for the switching apparatus, a subscribers station, means at the subscribers station for operating said electromagnetic releasing means, and means whereby when the subscriber initiates the release the said connection to battery is opened.

26; In a telephone system, a rotary connector having a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, a rotary magnet, an

energizing circuit for said rotary magnet, a difierential relay provided with means for breaking the energizing circuits of the said vertical and rotary magnets and then closing the energizing circuit of the release magnet, as set forth.

27. In a telephone system, a rotary connector having a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, a rotary magnet, an energizing'circuit for said rotary magnet, and a di'li'erential relay for controlling the circuits of said magnets.

28. In a telephone. system, a rotary connector adapted to select an idle one of a group of lines and having a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, and a differential relay provided with means for breaking the energizing circuit of the said vertical magnet and then closing the energizing circuit of the release magnet, as set forth.

29. In a telephone system,.a rotary connector having a release magnet, an energizing circuit for said release magnet, a vertical magnet, an energizing circuit for said vertical magnet, and a differential relay for controlling the circuits of said magnets.

30. In a telephone system, a rotary c0nnector liavinga release magnet, an energizing circuit for said release magnet. a rotary magnet, an energizing circuit for said rotary magnet, and a difl ercntial relay provided with means for breaking the energizing cirouit of the rotary magnet and then closing the energizing circuit of the release magnet, as set forth.

31. In a telephone system, a rotary con-- nector having a release magnet, an energizing circuit for said release magnet, a rotary magnet, an energizing circuit for said rotary magnet, and a difi'erential relay for controlling the circuits of said magnets.

In a telephone system, an automatic switch, a relay, a circuit for controlling said relay, :1 second relay, and switching means comprising a side switch whereby the first relay may he energized alone or the relays may be energized in series.

33. In .a telephone, cystem, aconnector switch, a relay, a circuit for controlling said relay, a second relay, and switching means comprising a side switch whereby the first relay may be energized alone or the relays may be energized in series.

34'. In a telephone system, a rotary connector switch, a relay, a circuit for controlling said relay, a second relay having a plurality of windings, a battery, said first relay normally connected to one terminal of said battery, one of said windings of said second relay being permanently connected with the same terminal of battery and disconnected from the other terminal thereof, means whereby the first relay may be shifted from the said terminal of battery to the terminal of the said winding of said second relay which is not connected with battery, and means for automatically rotating said switch to select an idle contact.

35. In a telephone system, a rotary connector switch, a relay, a circuit for controlling said relay, a second relay, switching means comprising a side switch whereby the first relay may be energized alone or the relays may be energized in series.

36. In a telephone system, a connector switch, a difierential relay, a line relay, a circuit for controlling said relay, a side switch wiper adapted to assume a first, second or third position, means whereby when the side switch wiper is in first or second position the line relay is energized alone, and when the side switch wiper is in third position the line relay and difi'erential relay are energize-d in series through said side switch.

37. In a telephone system, a connector switch, a front-bridge diiterential relay, a circuit for controlling said relay, a backbridge relay, operating magnets, a release magnet, a ringer relay, and means for energizing the same, said differential relay adapted when energized to prevent the said operating magnets and the back-bridge relay from energizing, and when denergized adapted to prevent the release magnet and ringer relay from energizing.

38. In a telephone system, a connector having automatic rotary motion and rotary motion under the control of the calling subscriber; a private magnet, a private wiper, private bank contacts adapted to be engaged by said private wiper, a grounded private bank conductor, an energizing circuit for the private magnet adapted to be main- I tained as long the private wiperis re-' tamed in connection wlth the grounded private bank conductor, whereby when the private Wiper passes onto an insulated contact the energizing circuit of the private magnet is broken.

" 39. In a telephone system, a connector having automatic rotary motion and rotary wiper, contacts allotted to said private wiper, means for sliding said private wiper along said contacts, said private magnet adapted to remain energized if the private wiper is on. a grounded private contact, and

an insulated private bank contact adapted to break said energizing circuit.

40. In a telephone system, a connector switch, line wipers, bank contacts adapted to be engaged by said wipers, means in said connector for carrying said wipers onto said contacts, a busy relay adapted to energize as soon as one of said. wipers engages one of said bank contact points, and a busy circuit controlled by said relay and adapted to be extended to the bank c'ontacts and to the line wipers when the said relay energizes.

41. In a telephone system, a common battery rotary connector provided with means for selecting an idle line and with a ringer relay, means for energizing this relay, and means whereby this relay remains de'energized during conversation over the talking circuit controlled thereby.

Signed by me at Chicago, Cook county, Illinois, this 31st day of May, 1907 VILSON L. CAMPBELL.

Witnesses:

' ARTHUR B. Srnnnr,

EDWARD D. FALES.

copies of this patent may, be obtained for five cents each, by addressing the "Commissioner or Intent, Washington, D. 0. 

